The “brown note” is an urban legend claiming a specific low-frequency sound can cause involuntary defecation or severe bowel discomfort in humans. This myth suggests exposure to such a sound would lead to an immediate loss of bowel function. The idea has circulated widely, often appearing in popular culture as a humorous or unsettling concept. This notion remains firmly in the realm of folklore, setting the stage for scientific inquiry into its viability.
Understanding Infrasound
Infrasound refers to sound waves with frequencies below the typical lower limit of human audibility, considered 20 Hertz (Hz). While humans cannot consciously hear these low frequencies, they can sometimes be felt as vibrations. The study of these waves, known as infrasonics, extends to frequencies as low as 0.1 Hz or even 0.001 Hz.
Infrasound originates from a variety of natural and artificial sources. Natural phenomena include large-scale events such as earthquakes, volcanic eruptions, severe weather like storms and tornadoes, ocean waves, avalanches, and meteors. On the human-made side, infrasound can be produced by heavy machinery, wind turbines, sonic booms from supersonic aircraft, explosions, and large musical instruments like pipe organs or specialized subwoofers. A distinguishing characteristic of infrasound is its ability to travel exceptionally long distances and penetrate physical barriers with minimal energy loss.
Infrasound and Human Physiological Responses
When humans are exposed to infrasound at high intensities, various physiological and psychological effects can occur, although involuntary defecation is not among them. Documented responses include:
- Feelings of unease, anxiety, or fear
- Sensations of pressure in the chest
- Fatigue
- Dizziness
- Visual distortions from vibrations affecting the eyeballs
Some studies also indicate reduced wakefulness and changes in blood pressure and heart rate at certain infrasound levels.
The television show MythBusters tested the “brown note” myth. They used powerful subwoofers to produce low frequencies down to 5 Hz and intensities up to 153 decibels. During their tests, subjects reported physical anxiety, shortness of breath, and mild nausea, consistent with intense low-frequency air pressure. However, none experienced involuntary bowel movements, leading the show to conclude the myth was “busted.”
While infrasound can induce discomfort or other physical sensations due to its ability to resonate with body parts at high intensities, the specific claim of the “brown note” causing immediate bowel evacuation is not supported by scientific evidence. Studies involving very high power levels, such as 160 decibels at 2-3 Hz, have caused symptoms like motor ataxia and nausea, but these remain distinct from the supposed brown note effect.
The Reality of Infrasound’s Effects
Scientific consensus indicates no credible evidence supports the existence of a “brown note” capable of inducing involuntary defecation in humans. No sound frequency or intensity achievable by common means has been shown to produce this specific effect.
The persistence of the “brown note” myth may stem from a misinterpretation of the real, albeit less dramatic, effects of infrasound, such as general discomfort or unease. Factors like the placebo effect, the power of suggestion, and its comedic value in entertainment also contribute to its enduring presence as an urban legend. While infrasound can indeed affect the human body, causing sensations like chest pressure or anxiety, these documented effects differ significantly from the unsubstantiated phenomenon described by the “brown note” myth.